Table 1.

Levels of evidence and recommendation grades

	Notation
Levels of evidence: Classification based on study design
Systematic review, meta-analysis, randomized controlled trial	Randomized controlled trial
Non-randomized controlled studies	Non-randomized controlled trial
Case series etc.	Uncontrolled studies
Expert opinion	Expert opion
Recommendation grades: Classification based on the balance of benefits and harms and the scope of application
When it is recommended to apply to most subjects	General recommendation
When it is recommended to apply with limitations based on certain conditions among the subjects	Limited recommendation